Postoperative pain is a common complication in the perioperative period of surgery. It not only reduces patients’ quality of life, but also easily induces adverse events such as pulmonary infection and deep vein thrombosis, hindering the clinical implementation of the concept of enhanced recovery after surgery. As a hydrophilic opioid, intrathecal morphine (ITM) has the advantages of long residence time in cerebrospinal fluid and high analgesic potency, which can achieve long‑term analgesia for 24–48 hours, especially with a significant effect on visceral pain control. It has become a core component of the multimodal analgesia system. This paper systematically reviews the development status, pharmacological basis and core advantages of ITM in postoperative analgesia, focuses on its clinical application optimization strategies and targeted application schemes in different types of surgery, analyzes the shortcomings of current research, and prospects future research directions, so as to provide accurate and comprehensive practice guidance for clinicians.